| 1. |
- Kahanpää, Henrik, et al.
(författare)
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Convective vortices and dust devils at the MSL landing site : annual variability
- 2016
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Ingår i: Journal of Geophysical Research - Planets. - 2169-9097 .- 2169-9100. ; 121:8, s. 1514-1549
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Tidskriftsartikel (refereegranskat)abstract
- Two hundred fifty-two transient drops in atmospheric pressure, likely caused by passing convective vortices, were detected by the Rover Environmental Monitoring Station instrument during the first Martian year of the Mars Science Laboratory (MSL) landed mission. These events resembled the vortex signatures detected by the previous Mars landers Pathfinder and Phoenix; however, the MSL observations contained fewer pressure drops greater than 1.5 Pa and none greater than 3.0 Pa. Apparently, these vortices were generally not lifting dust as only one probable dust devil has been observed visually by MSL. The obvious explanation for this is the smaller number of strong vortices with large central pressure drops since according to Arvidson et al. [2014] ample dust seems to be present on the surface. The annual variation in the number of detected convective vortices followed approximately the variation in Dust Devil Activity (DDA) predicted by the MarsWRF numerical climate model. This result does not prove, however, that the amount of dust lifted by dust devils would depend linearly on DDA, as is assumed in several numerical models of the Martian atmosphere, since dust devils are only the most intense fraction of all convective vortices on Mars, and the amount of dust that can be lifted by a dust devil depends on its central pressure drop. Sol-to-sol variations in the number of vortices were usually small. However, on 1 Martian solar day a sudden increase in vortex activity, related to a dust storm front, was detected.
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| 2. |
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| 3. |
- Lillis, Robert J., et al.
(författare)
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MOSAIC: A satellite constellation to enable groundbreaking mars climate system science and prepare for human exploration
- 2021
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Ingår i: Planetary Science Journal. - : Institute of Physics (IOP). - 2632-3338. ; 2:5
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Tidskriftsartikel (refereegranskat)abstract
- The Martian climate system has been revealed to rival the complexity of Earth's. Over the last 20 yr, a fragmented and incomplete picture has emerged of its structure and variability; we remain largely ignorant of many of the physical processes driving matter and energy flow between and within Mars' diverse climate domains. Mars Orbiters for Surface, Atmosphere, and Ionosphere Connections (MOSAIC) is a constellation of ten platforms focused on understanding these climate connections, with orbits and instruments tailored to observe the Martian climate system from three complementary perspectives. First, low-circular near-polar Sun-synchronous orbits (a large mothership and three smallsats spaced in local time) enable vertical profiling of wind, aerosols, water, and temperature, as well as mapping of surface and subsurface ice. Second, elliptical orbits sampling all of Mars' plasma regions enable multipoint measurements necessary to understand mass/energy transport and ion-driven escape, also enabling, with the polar orbiters, dense radio occultation coverage. Last, longitudinally spaced areostationary orbits enable synoptic views of the lower atmosphere necessary to understand global and mesoscale dynamics, global views of the hydrogen and oxygen exospheres, and upstream measurements of space weather conditions. MOSAIC will characterize climate system variability diurnally and seasonally, on meso-, regional, and global scales, targeting the shallow subsurface all the way out to the solar wind, making many first-of-their-kind measurements. Importantly, these measurements will also prepare for human exploration and habitation of Mars by providing water resource prospecting, operational forecasting of dust and radiation hazards, and ionospheric communication/positioning disruptions.
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| 4. |
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| 5. |
- Moores, John E., et al.
(författare)
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Atmospheric movies acquired at the Mars Science Laboratory landing site : Cloud Morphology, Frequency and Significance to the Gale Crater Water Cycle and Phoenix Mission Results
- 2015
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Ingår i: Advances in Space Research. - : Elsevier BV. - 0273-1177 .- 1879-1948. ; 55:9, s. 2217-2238
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Tidskriftsartikel (refereegranskat)abstract
- We report on the first 360 sols (LS 150° to 5°), representing just over half a Martian year, of atmospheric monitoring movies acquired using the NavCam imager from the Mars Science Laboratory (MSL) Rover Curiosity. Such movies reveal faint clouds that are difficult to discern in single images. The data set acquired was divided into two different classifications depending upon the orientation and intent of the observation. Up to sol 360, 73 Zenith Movies and 79 Supra-Horizon Movies have been acquired and time-variable features could be discerned in 25 of each. The data set from MSL is compared to similar observations made by the Surface Stereo Imager (SSI) onboard the Phoenix Lander and suggests a much drier environment at Gale Crater (4.6°S) during this season than was observed in Green Valley (68.2°N) as would be expected based on latitude and the global water cycle. The optical depth of the variable component of clouds seen in images with features are up to 0.047 ± 0.009 with a granularity to the features observed which averages 3.8 degrees. MCS also observes clouds during the same period of comparable optical depth at 30 and 50 km that would suggest a cloud spacing of 2.0 to 3.3 km. Multiple motions visible in atmospheric movies support the presence of two distinct layers of clouds. At Gale Crater, these clouds are likely caused by atmospheric waves given the regular spacing of features observed in many Zenith movies and decreased spacing towards the horizon in sunset movies consistent with clouds forming at a constant elevation. Reanalysis of Phoenix data in the light of the NavCam equatorial dataset suggests that clouds may have been more frequent in the earlier portion of the Phoenix mission than was previously thought.
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| 6. |
- Moores, John E., et al.
(författare)
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Observational evidence of a suppressed planetary boundary layer in northern Gale Crater, Mars as seen by the Navcam instrument onboard the Mars Science Laboratory rover
- 2015
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Ingår i: Icarus. - : Elsevier BV. - 0019-1035 .- 1090-2643. ; 249, s. 129-142
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Tidskriftsartikel (refereegranskat)abstract
- The Navigation Cameras (Navcam) of the Mars Science Laboratory rover, Curiosity, have been used to examine two aspects of the planetary boundary layer: vertical dust distribution and dust devil frequency. The vertical distribution of dust may be obtained by using observations of the distant crater rim to derive a line-of-sight optical depth within Gale Crater and comparing this optical depth to column optical depths obtained using Mastcam observations of the solar disc. The line of sight method consistently produces lower extinctions within the crater compared to the bulk atmosphere. This suggests a relatively stable atmosphere in which dust may settle out leaving the air within the crater clearer than air above and explains the correlation in observed column opacity between the floor of Gale Crater and the higher elevation Meridiani Planum. In the case of dust devils, despite an extensive campaign only one optically thick vortex (τ=1.5±0.5×10-3) was observed compared to 149 pressure events > 0.5Pa observed in REMS pressure data. Correcting for temporal coverage by REMS and geographic coverage by Navcam still suggests 104 vortices should have been viewable, suggesting that most vortices are dustless. Additionally, the most intense pressure excursions observed on other landing sites (pressure drop >2.5Pa) are lacking from the observations by the REMS instrument. Taken together, these observations are consistent with pre-landing circulation modeling of the crater showing a suppressed, shallow boundary layer. They are further consistent with geological observations of dust that suggests the northern portion of the crater is a sink for dust in the current era.
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| 7. |
- Pearce, Neil E, et al.
(författare)
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IARC Monographs : 40 Years of Evaluating Carcinogenic Hazards to Humans
- 2015
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Ingår i: Journal of Environmental Health Perspectives. - : Environmental Health Perspectives. - 0091-6765 .- 1552-9924. ; 123:6, s. 507-514
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Recently the International Agency for Research on Cancer (IARC) Programme for the Evaluation of Carcinogenic Risks to Humans has been criticized for several of its evaluations, and also the approach used to perform these evaluations. Some critics have claimed that IARC Working Groups' failures to recognize study weaknesses and biases of Working Group members have led to inappropriate classification of a number of agents as carcinogenic to humans.OBJECTIVES: The authors of this paper are scientists from various disciplines relevant to the identification and hazard evaluation of human carcinogens. We have examined here criticisms of the IARC classification process to determine the validity of these concerns. We review the history of IARC evaluations and describe how the IARC evaluations are performed.DISCUSSION: We conclude that these recent criticisms are unconvincing. The procedures employed by IARC to assemble Working Groups of scientists from the various discipline and the techniques followed to review the literature and perform hazard assessment of various agents provide a balanced evaluation and an appropriate indication of the weight of the evidence. Some disagreement by individual scientists to some evaluations is not evidence of process failure. The review process has been modified over time and will undoubtedly be altered in the future to improve the process. Any process can in theory be improved, and we would support continued review and improvement of the IARC processes. This does not mean, however, that the current procedures are flawed.CONCLUSIONS: The IARC Monographs have made, and continue to make, major contributions to the scientific underpinning for societal actions to improve the public's health.
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| 8. |
- Thompson, Paul M., et al.
(författare)
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The ENIGMA Consortium : large-scale collaborative analyses of neuroimaging and genetic data
- 2014
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Ingår i: BRAIN IMAGING BEHAV. - : Springer Science and Business Media LLC. - 1931-7557 .- 1931-7565. ; 8:2, s. 153-182
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Tidskriftsartikel (refereegranskat)abstract
- The Enhancing NeuroImaging Genetics through Meta-Analysis (ENIGMA) Consortium is a collaborative network of researchers working together on a range of large-scale studies that integrate data from 70 institutions worldwide. Organized into Working Groups that tackle questions in neuroscience, genetics, and medicine, ENIGMA studies have analyzed neuroimaging data from over 12,826 subjects. In addition, data from 12,171 individuals were provided by the CHARGE consortium for replication of findings, in a total of 24,997 subjects. By meta-analyzing results from many sites, ENIGMA has detected factors that affect the brain that no individual site could detect on its own, and that require larger numbers of subjects than any individual neuroimaging study has currently collected. ENIGMA's first project was a genome-wide association study identifying common variants in the genome associated with hippocampal volume or intracranial volume. Continuing work is exploring genetic associations with subcortical volumes (ENIGMA2) and white matter microstructure (ENIGMA-DTI). Working groups also focus on understanding how schizophrenia, bipolar illness, major depression and attention deficit/hyperactivity disorder (ADHD) affect the brain. We review the current progress of the ENIGMA Consortium, along with challenges and unexpected discoveries made on the way.
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| 9. |
- Niemi, MEK, et al.
(författare)
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- 2021
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swepub:Mat__t
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